Removed inverse_fast, probably not going to use it in tight loops

1 files changed, 51 insertions, 0 deletions

diff --git a/old/inverse_fast.c b/old/inverse_fast.c
new file mode 100644
index 0000000..13ace58
--- /dev/null
+++ b/old/inverse_fast.c
@@ -0,0 +1,51 @@
+_static_inline cube_fast_t
+cleanaftershuffle(cube_fast_t c)
+{
+        __m256i b;
+
+        b = _mm256_set_epi8(
+                ~0, ~0, ~0, ~0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+                ~0, ~0, ~0, ~0, ~0, ~0, ~0, ~0, 0, 0, 0, 0, 0, 0, 0, 0
+        );
+
+        return _mm256_andnot_si256(b, c);
+}
+
+_static_inline cube_fast_t
+inverse_fast(cube_fast_t c)
+{
+        /* Method taken from Andrew Skalski's vcube[1]. The addition sequence
+         * was generated using [2].
+         * [1] https://github.com/Voltara/vcube
+         * [2] http://wwwhomes.uni-bielefeld.de/achim/addition_chain.html
+         */
+        cube_fast_t v3, vi, vo, vp, ret;
+
+        v3 = _mm256_shuffle_epi8(c, c);
+        v3 = _mm256_shuffle_epi8(v3, c);
+        vi = _mm256_shuffle_epi8(v3, v3);
+        vi = _mm256_shuffle_epi8(vi, vi);
+        vi = _mm256_shuffle_epi8(vi, vi);
+        vi = _mm256_shuffle_epi8(vi, v3);
+        vi = _mm256_shuffle_epi8(vi, vi);
+        vi = _mm256_shuffle_epi8(vi, vi);
+        vi = _mm256_shuffle_epi8(vi, vi);
+        vi = _mm256_shuffle_epi8(vi, vi);
+        vi = _mm256_shuffle_epi8(vi, c);
+        vi = _mm256_shuffle_epi8(vi, vi);
+        vi = _mm256_shuffle_epi8(vi, vi);
+        vi = _mm256_shuffle_epi8(vi, vi);
+        vi = _mm256_shuffle_epi8(vi, vi);
+        vi = _mm256_shuffle_epi8(vi, vi);
+        vi = _mm256_shuffle_epi8(vi, v3);
+        vi = _mm256_shuffle_epi8(vi, vi);
+        vi = _mm256_shuffle_epi8(vi, c);
+
+        vo = _mm256_and_si256(c, _mm256_or_si256(_eo_avx2, _co2_avx2));
+        vo = _mm256_shuffle_epi8(vo, vi);
+        vp = _mm256_andnot_si256(_mm256_or_si256(_eo_avx2, _co2_avx2), vi);
+        ret = _mm256_or_si256(vp, vo);
+        ret = cleanaftershuffle(ret);
+        
+        return invertco_fast(ret);
+}